Changeset 17155 for stable/HeuristicLab.Problems.DataAnalysis.Symbolic

Timestamp:

07/23/19 20:15:32 (5 years ago)

Author:

gkronber

Message:

#2948: merged r17125 (support for symbolic derivation of tanh) from trunk to stable

Location:

stable

Files:

• . (modified) (1 prop)
• HeuristicLab.Problems.DataAnalysis.Symbolic (modified) (1 prop)
• HeuristicLab.Problems.DataAnalysis.Symbolic/3.4/Converters/DerivativeCalculator.cs (modified) (1 diff)

stable/HeuristicLab.Problems.DataAnalysis.Symbolic/3.4/Converters/DerivativeCalculator.cs

@@ -179 +179 @@
         var u = (ISymbolicExpressionTreeNode)branch.GetSubtree(0).Clone();
         return Div(fxp, Square(Cosine(u)));
+      }
+      if (branch.Symbol is HyperbolicTangent) {
+        // tanh(f(x))' = f(x)'sech²(f(x)) = f(x)'(1 - tanh²(f(x)))
+        var fxp = Derive(branch.GetSubtree(0), variableName);
+        var tanh = (ISymbolicExpressionTreeNode)branch.Clone();
+        return Product(fxp, Subtract(CreateConstant(1.0), Square(tanh)));
       }
       throw new NotSupportedException(string.Format("Symbol {0} is not supported.", branch.Symbol));